1. Field of the Invention
The present invention relates to machines for screening a particulate, granulate or any other material. Particularly, the present invention relates to a screener that is portable and compact enough to be contained and moved on a dump body. More particularly the present invention is a screener compact enough to be mounted over the dump body on a standard dump truck. Even more particularly, the present invention relates to a screener that can support itself independent of the vehicle""s support structure or power source.
2. Description of the Prior Art
Particle screeners are useful in the field of construction excavation for separating the components of soil. By using a screener soil can be broken up into its components of different particle size such as topsoil, sand, rocks, and larger organics such as plant matter. Once the components of the soil have been separated the product can be used in its proper application. Currently the only designs available are either so large that it is required that they are towed to location or are built to a specialized truck.
Several portable screeners have been created for particle separation. Current portable screeners are either towed to the site or are fixed to a specialized vehicle dedicated to moving the screener. There have been no devices created for a vehicle mounted portable screener that can also function independently from the mounting vehicle.
U.S. Pat. No. 6,029,822 (Allan Skoropa) discloses a vibratory screening device including a frame and a screen, supported by the frame, for separating undersize and oversize material. A vibratory device, consisting of an eccentric shaft, coupled to the screen that includes a first output shaft with an axis of rotation that oscillates with relation to the frame. The vibratory device oscillates the screen as the first output shaft is rotated. A driver includes a second output shaft with an axis of rotation that includes a second output shaft with an axis of rotation that is fixed relative to the frame. The driver rotates the first output shaft. Preferably, the connector includes a first universal joint, a sliding spine shaft, and a second universal joint. The driver preferably includes an engine, a centrifugal clutch coupled to the first output shaft, a sheave, and an endless belt connecting the centrifugal clutch to the sheave. The disadvantage of this device is that it is not a truck dump-body mounted unit.
U.S. Pat. No. 5,294,065 (Timothy O. Harms) discloses a high rate portable combination screening/dosing/mixing plant that is mounted on a single tractor-trailer for highway travel. The apparatus is used in soil remediation. The invention comprises of an apparatus train for preliminary particle separation, a hopper, a shredder, particle size screener, an apparatus for mixing, and a conveyor belt for elevating product to desired locations. The disadvantage in this apparatus is that it must be towed to the site.
U.S. Pat. No. 5,433,575 (John Milstead) discloses a method of erecting a portable asphalt production plant. The asphalt production plant comprises of upper and lower subassemblies that are attached to a trailer for towing the production plant to the worksite. Once at the worksite the frame is detached from the trailer and the upper subassembly is positioned on top of the lower subassembly. The size of this apparatus dictates that it must be towed to the worksite.
The disadvantages of the currently available screeners are that they require a specialized truck and additional driver to transport them to the excavation sites. This is problematic because in addition to the added costs of obtaining and using the equipment and drivers for transporting the particle screener, the equipment is no longer readily available for performing other tasks. Owners of screeners often own vehicles, i.e. dump trucks, for towing the screeners. The advantage of mounting equipment to a dump body is it allows for the same vehicle to tow additional equipment by trailer thus reducing the number of vehicles and drivers necessary to transport the screener.
Therefore what is needed is a portable screener that can be easily mounted onto and removed from atop the dump body of a dump truck. What is further needed is a dump-body mounted portable screener that is capable of functioning on its own structural supports or legs. What is still further needed is a portable vehicle mounted screener that can function under either its own power source or the power source provided by the vehicle on which it is mounted.
It is an objective of the present invention to provide a particle screener for removably mounting atop the dump body of a dump truck. It is a further objective of the present invention to provide a portable screener that can be mounted atop the dump body of a dump truck and be capable of functioning on its own structural supports or legs to support the portable screener. It is still a further objective of the present invention that the screener is capable of functioning under either its own power source or a power source provided by the mounting vehicle.
The present invention achieves these and other objectives by providing various structural features that make mounting the particle screener onto a dump body of a dump truck, possible. The vehicle-mounted screener includes a support frame, at least one vibratory screen deck, a plurality of springs, and an agitation/oscillating source. The support frame provides support for the vibratory screen deck and the mechanism for mounting the screener to a dump body. The springs hold the vibratory screen deck to the screener frame and return the screen to its original position during agitation/oscillation. The screen separates the particles by particle size. As used herein xe2x80x9cparticlexe2x80x9d refers to any material, which is primarily non-continuous and largely comprises solid or semisolid pieces. The particulate material referred to may range from uniformly sized grains such as sand to a sill or compost having entities of widely varying sizes and compositions including material of animal, vegetable and mineral origin. Moisture or other liquid may be associated with the solids. The agitation/oscillation source provides motion to the vibratory screen deck.
The support frame of the present invention provides a stationary base for the vibratory screen deck and for supporting the screener atop the dump body of a dump truck. Optionally, the screener may be provided with a mechanism to support the screener when the screener is not mounted atop the dump body of a dump truck. The support frame is constructed from elongated tubing. The tubing may be square, rectangular or circular in cross section. The cross pieces that support the screener over the dump body are pieces of square tubing that are rotated in a manner to create a diamond cross section. This configuration presents angled crosspieces that prevent material from collecting on the crosspieces as the material is screened into the dump body from the vibratory screen deck. The support frame may be described as having a rectangular shape with extending ends from two sides of the rectangular structure. The dimensions of the support frame are compatible and sized to the dump body over which it is to be mounted. The extending ends are used to support the screener atop the dump body of the dump truck.
The frame mounts are configured onto sideboards that are mounted along the sides of the dump body. The extending ends are fitted into the frame mounts for supporting the screener over the dump body allowing the screened material to collect within the dump body. The sideboards have at least four shaped receiving connectors, i.e. frame mounts, for supporting the support frame of the screener. The receiving connectors in the sideboards may be either shaped slots or shaped brackets. The shaped slots are formed by cutting the slots into the sideboards. The shaped brackets are formed by attaching the brackets to the sideboards. The shape of the brackets or slots is compatible with the extending ends of the support frame. The sideboards are fitted to the bed of the vehicle and the screener frame connects to the frame mounts incorporated into the sideboards. A combination of slots and brackets at different heights may be used to tilt the screener or the screener can be mounted parallel to the bed of the vehicle by placing the frame mounts at the same height.
The support frame of the screener also has provisions to support the screener when removed from the dump body. The screener frame may have a set of legs for supporting the screener independent of the dump body. The legs may be pivotally attached, removably attached, or telescopingly attached to the screen frame. The legs are hydraulically, electrically, or mechanically actuated. When the legs are not needed as when the screener is left atop the dump body for use, they may be optionally removed from the screener or positioned in a manner that would not interfere with the use of the screener. Additionally the screener has a hopper that is shaped in a manner to guide the raw material onto the vibratory screen. The hopper may be attached to the screen deck to facilitate loading of raw material and for containing raw material to the screen. Another embodiment of the hopper design is a detachable hopper that mounts to the screener frame by way of hopper supports.
The springs attach the support frame to the vibratory screen deck and return the vibratory screen deck back to its original position during agitation. Leaf springs, coil springs or a combination of springs may be employed. Bumper stops may also be used to help return the vibratory screen deck to its starting position. The springs are mounted from the side of the support frame to the side of the vibratory screen deck. The springs may also be a combination of a coil and leaf type spring. If the combination is used the leaf spring is preferably the main vibratory action spring and the coil spring would provide the return action. A leaf spring setup is quieter than a coil spring setup. The springs position the vibratory deck above the screener frame in a manner that allows the particles to fall through the screener and collect in the dump body of the dump truck.
The vibratory screen deck includes a screen, a screen deck frame, and screen retainers. The screen separates the particles through a mesh size chosen by the user. Six cross-bracing members reinforce the screen deck frame. The cross bracing members are parallel to the shorter ends, or width, of the screen deck. In addition to the cross bracing members, there is screen bracing that supports the screen. The screen bracing is configured such that it causes the screen to have a continuous peak or crown down the entire length of the screen. The continuous crown is positioned parallel to the length of the screen deck. The crown ensures that the particles spread out and do not pool in the center of the vibratory screen during use. Crowning is achieved by positioning the tallest screen bracing down the center of the screen parallel to the length dimension of the screen deck with an array of shorter screen bracing to either side of the center. Rubber tubing for protecting the screen bracing from wear as well as keeping the apparatus quieter may be used to cover the screen bracing and to support the screen.
A screen retainer or bracket is used to attach the screen to the screen deck. The screen bracket is an elongated strip that may be flat or have an L or C shape. The screen is held in place by bolting at least two screen brackets, which run along the longer end or length of the screen deck, to the inside of the screen deck. The screen retainer holds the screen to the screen deck by applying pressure to the edges of screen and compressing the screen against the frame of the screen deck when the retainer is bolted to the sides of the screen deck.
The screen deck also incorporates provisions for attaching more than one vibratory screen deck to the screener. In embodiments where the hopper is not permanently secured to the screen deck, additional screen decks may be attached by bolting or clamping the additional screen deck to the previous screen deck. This enables one to incorporate different mesh sizes to further separate material.
The screener also includes an agitation mechanism. The agitation mechanism includes an elongated housing that encloses a drive motor coupled to a vibratory shaft supported by bearings. The drive motor has power connections for receiving the electrical or hydraulic power required to drive the drive motor. The vibratory shaft may be a cylindrical shaft with an off-center rotational axis, or a rectangular shaft with an off-center rotational axis, or a square shaft with an off-center rotational axis, or a shaped shaft with an attachable counterweight that is attached along the length of the vibratory shaft where the shaped shaft may or may not have an off-center rotational axis. The mechanism also includes a coupling device to couple the vibratory shaft to the drive motor.
The elongated housing contains the drive motor, vibratory shaft and support bearings and protects the working components from the outside weather, screening material and the like, thus extending component life. The elongated housing is attached to the bottom of the screen deck across its width at the screen decks approximate center. The elongated housing conveys the motion produced by the off-balanced, rotating shaft to the screen deck causing the screen deck to vibrate. For maintaining the mechanics within the enclosed housing there is a service cover positioned along the length of the enclosed housing that can be removed to provide access to the vibratory mechanism components for repair and replacement.
The rotating off-balanced shaft is configured to provide an off-balance rotation. To provide a shaft with an off-balanced weight, a steel shaft with a square cross section may be produced with milled ends either off-center with the rotational axis of the shaft or not. In either case, adding more off-center weight to the rotating shaft may be accomplished by tapping bolt holes into one face of the shaft to provide a mechanism for fastening an offset weight to the shaft. The offset weight of the shaft when rotated creates an elliptical motion that causes the vibratory screen deck to move up and down. A second embodiment of the rotating, off-balanced shaft includes a machined steel bar with circular cross-sectional ends in line with the body of the bar, the offset weight provided only by the addition of extra weight of the tapped bolts. A third embodiment of the rotating, off-balanced shaft includes a set of flywheels attached by a shaft offset from the centerline of the flywheels. The offset weight provided by the offset shaft when rotated creates an elliptical motion similar to that created by the bolt heads. The elliptical motion of the vibratory shaft is applied to the elongated housing by a set of bearings coupling the elongated housing to the rotating shaft.
Another variation of the above design is to incorporate two synchronized motors located at each end enclosed within the enclosed housing. A further variation is to incorporate one motor centrally positioned within the enclosed housing driving two offset shafts on either side of the centrally positioned motor. Another variation for providing agitation to the screen is to incorporate a shaft with an exposed offset counter weight. By positioning a counter weight at the end of a shaft and rotating the same effect can be achieved.
In use, the user would mount sideboards having receiving connectors to a vehicle dump body. The user then positions the extending ends of the support frame of the screener into the receiving connectors of the sideboards. The screener is secured to the vehicle by connecting the support frame of the screener to the vehicle frame with tie downs as is well known in the art. At this point, the user may transport the screener to the worksite. For operating the screener while mounted atop the dump body of the vehicle, the user connects a power source to the drive motor of the screener""s agitation mechanism. The agitation mechanism can be powered by using the power sources incorporated in the vehicle whether it is an electrical or hydraulic power source. If the user desires to operate the screener independently from the vehicle, the user may erect the screener using the screener""s support structure or legs and connect an independent power source to the drive motor of the agitation mechanism. Once the user decides in which configuration he wants to operate the screener, the user starts the drive motor of the screener and adds the raw material into the hopper or directly onto the vibratory screen by using a frontloader or other means to move the raw material.
Additional advantages and embodiments of the present invention will be set forth in part in the detailed description which follows and in part will be apparent from the description which follows or may be learned by practice for the invention. It is understood that the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.